Rexolvers

A lightweight DNS resolver aggregation tool that collects DNS resolver IP addresses from multiple public and trusted sources.

Installation

Build from source

git clone https://github.com/karanshergill/rexolvers
cd rexolvers
go build -o rexolvers .

Docker

# Build the Docker image
docker build -t rexolvers .

# Or pull from a registry (if available)
docker pull your-registry/rexolvers:latest

Usage

Local Binary

Basic Operations

Process public resolvers:

./rexolvers --public

Process trusted resolvers:

./rexolvers --trusted

Process both types:

./rexolvers --all

Database Operations

Save to database:

./rexolvers --trusted --db

Save only to database (skip file):

./rexolvers --public --db --file=false

List resolvers from database:

# List trusted resolvers
./rexolvers --list=trusted

# List public resolvers
./rexolvers --list=public

# List all resolvers
./rexolvers --list=all

Show database statistics:

./rexolvers --stats

Docker

Docker usage allows you to run the application in a containerized environment and export the database to your host machine.

Setup

# Create directory for database export
mkdir -p ./docker-output

# Build the Docker image
docker build -t rexolvers .

Basic Operations

Process all resolvers and save to database:

docker run -v $(pwd)/docker-output:/app/data rexolvers --all --db

Process public resolvers only:

docker run -v $(pwd)/docker-output:/app/data rexolvers --public --db

Process trusted resolvers only:

docker run -v $(pwd)/docker-output:/app/data rexolvers --trusted --db

Database Operations

List resolvers from exported database:

# List all resolvers
docker run -v $(pwd)/docker-output:/app/data rexolvers --list=all

# List trusted resolvers
docker run -v $(pwd)/docker-output:/app/data rexolvers --list=trusted

# List public resolvers
docker run -v $(pwd)/docker-output:/app/data rexolvers --list=public

Show database statistics:

docker run -v $(pwd)/docker-output:/app/data rexolvers --stats

Accessing Exported Database

After running with the --db flag, the SQLite database will be available at:

./docker-output/resolvers.db

You can then:

• Copy this database file anywhere you need it
• Query it directly with sqlite3: sqlite3 ./docker-output/resolvers.db
• Use it with other tools that accept SQLite databases

Docker Examples

# Complete workflow - fetch data and export database
docker build -t rexolvers .
mkdir -p ./docker-output
docker run -v $(pwd)/docker-output:/app/data rexolvers --all --db

# Check what was collected
docker run -v $(pwd)/docker-output:/app/data rexolvers --stats

# Export trusted resolvers for use with other tools
docker run -v $(pwd)/docker-output:/app/data rexolvers --list=trusted > trusted_resolvers.txt

Command Line Flags

Flag	Description	Default
--public	Process public resolvers	false
--trusted	Process trusted resolvers	false
--all	Process both public and trusted resolvers	false
--db	Save resolvers to SQLite database	false
--file	Save resolvers to text files	true
--list	List resolvers from database (public|trusted|all)	""
--stats	Show database statistics	false

Output Files

• public_resolvers.txt: Contains public DNS resolver IPs
• trusted_resolvers.txt: Contains trusted DNS resolver IPs
• resolvers.db: SQLite database with all resolvers

Database Schema

The SQLite database uses the following schema:

CREATE TABLE resolvers (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    ip_address TEXT UNIQUE NOT NULL,
    resolver_type TEXT NOT NULL,
    source_url TEXT,
    added_at DATETIME DEFAULT CURRENT_TIMESTAMP
);

Configuration

The tool uses a YAML configuration file located at:

• Linux/macOS: $HOME/.config/rexolvers/config.yaml
• Windows: %APPDATA%\rexolvers\config.yaml

Integration Examples

Use with massdns

# Get all resolvers from database
./rexolvers --list=all > resolvers.txt
massdns -r resolvers.txt -t A domains.txt

Query database directly

# Using sqlite3 command line
sqlite3 resolvers.db "SELECT COUNT(*) FROM resolvers WHERE resolver_type='trusted';"

Examples

# Initial setup - fetch and save everything
./rexolvers --all --db

# Daily update - refresh database only
./rexolvers --all --db --file=false

# Export for specific tool
./rexolvers --list=trusted > my_resolvers.txt

# Check what's in database
./rexolvers --stats

License

This project is licensed under the MIT License.